A constricted plasma arc can reach temperatures up to 25000 degrees Celsius (45032°F). Given this evidence, it can be concluded that a Lightsaber in Fortnite can reach temperatures of up to 25000 degrees Celsius (45032°F).
Is a Darksaber a lightsaber in Fortnite?
An ancient lightsaber in Fortnite that serves as a powerful symbol of leadership to the Mandalorians, the Darksaber is a unique weapon with a black-energy blade lined with a crackling white edge.